Wednesday 1 Dec:

 Target: Gas Laws

 Journal: (review)

  • Waves transport matter.

  • There must be a medium (solid, liquid or gas) for a wave to travel through.

  • Waves have energy, the longer the wave, the greater the energy.

  • Shorter l (length of wave) travel faster than longer l waves in the same medium.

  • Different colors of light are different types of waves.

  • Waves don't change frequency when going from one medium to another medium, only velocity and l (wavelength) change.

 

 

 

CH #12:

 

1. An ideal gas in a closed container initially has volume V, pressure P1. and Kelvin temperature T. If the Pressure is changed to 4P1 and the T is halved, what is the new volume?

 

 

 

 

 

P1V1/T1 = P2V2/T2

           =  4P1(V2)/(.5)(T1)

V2 =  1/8V1

 

 

2.  If the average kinetic energy of the molecules in an ideal gas at a temperature of 100 K is E, the average kinetic energy at a temperature of 500 K is?

 

2. KE = (3/2)KBT     (KB is Boltzmann's constant = 1.38 x 10-23)

à  Therefore, Temp is directly related to KE

     if T goes up 5 times, so does KE

 

 

 

 

 

 

 

3. If the number molecules is reduced in a container by 1/3 (but same pressure and volume), what will this do to the temperature and the KE?

 

 

 

 

3. Temp:  PV = nRT:

   PV is constant, as n (moles of the gas) goes down, so T  will go up proportionally (R is a constant; universal gas constant)

 

 

 

 

 

4. If the mass of each molecule is decreased by 1/2, but the temperature is held constant what happens to:

a. Velocity

b. KE of the gas molecules?

 

 

4. a. V:  Vrms = √(3kT/m) à decrease the mass by 1/2, you  increase the Vrms by √(1/.5) or √(2) 

 

  b.  KE:   KE = (3/2)KBT :

  à T is constant so KE is constant

 

 

 

 

 

5. If the volume is reduced to ½ the original volume, but the pressure is held constant, how does this affect

a) temperature

b) Vrms?

 

 

5. a. Temp:  PV = nRT:

    à P and nR are constant, so

as V goes down by ½, so does Temperature.

                        `

          b. Vrms = √(3kT/m)

                     à as T is decrease by 0.5,

                       the Vrms decreases by  √.5

           

 

 

 

 

 

7. Find the new ___ of a 1.0m sq metal plate when the temperature is decreased. (what formulas are used)

 

a. length on one side

b. area (without the hole)

c. area of a hole in the middle of the plate

d. volume of a 1.0 m sphere

 

a.      one side

 

 

 

 

 

 

 

 

 

Shortens length by: (L)(a)(DT)

 

b.      Area Metal .

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(area)(2a)(DT)

 

 

 

 

 

 

 

c.      The hole in the above plate.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

lessens area of plate by : (Area)(2a)(DT)

 

 

d.      Sphere:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

lessens volume of plate by : (V)(3a)(DT)

                                              

 

 

 

 

 

 

 

Video: Boyle’s Law, b. Charles Law and c. Gay-Lussac’s Laws?  (Animated Gas Lab )

 

 

 http://www.grc.nasa.gov/WWW/K-12/airplane/Animation/frglab.html

 

 

 

 

 

 

 

 

 

 

a.   Length shortens by: (L)(a)(DT)

 

b.     Area reduced:  (area)(2a)(DT)

 

 

c.      Sphere lessens volume: (V)(3a)(DT)